DMC Evaluation Quiz Solution - MAE 342 - Design of...

MAE 342 - Design of Mechanical ComponentsSolutions to Evaluation Quiz 1: In Figure 1, for static equilibrium, F2must be (circle the correct answer): (a) 10 N, (b) 10300tan()N, (c) 10300cot()N, (d) cannot be determined. •For a force balance in horizontal direction:F13010cos=. •For a force balance in vertical direction:FF1230sin=. •Eliminating F1: F21030=tan. 30010 NF1F21 N1 NAASection A-A0.1 mm0.2 mmFigure 1 Figure 2 2. In Figure 2, the stress in X-section A-A (assumed to be uniform) is 50 N/mm2. •Stress = Force/ Area (Stress is proportional to force but inversely proportional to the area. Makes sense?). σ==1010 250/( .* . )3. In Figure 2, if the Young’s modulus (E) of the material is 50,000 N/mm2, and the length of the bar is 100 mm, the increasein length of the bar is approximately 0.1 mm. •Increase in length is proportional to strain and total length. ∆ll=ε•Strain is unit-less, and is proportional to stress but inversely proportional to Young’s Modulus, since Young’s modulus is a measure of the material’s stiffness.

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